Now, through his Web site Wolfgang’s Vault (Wolfgang was Graham’s given name), Sagan is streaming the collection through what he calls Vault Radio. It is amazing stuff. Hear Grace Slick sing “Somebody to Love” in 1966 with not Jefferson Airplane, but her earlier group, Great Society (performing on the same bill with Jefferson Airplane). You’ll find early recordings of The Allman Brothers, Elvis Costello and Taj Mahal, as well as classics by a range of rock and R&B; greats from Chuck Berry and Booker T. to The Staple Singers and Frank Zappa.